The standards — what to read, in what order, and what it costs.
Start with ETSI, and all of it is free. ETSI publishes every deliverable at no charge, and the ASN.1 modules are on its GitLab. IEEE, SAE, ISO and CEN are paid. What follows is the order that actually works, and what each document is for.
All of it is free, and the directory listing is the fastest version check.
ETSI publishes every deliverable at no charge. The direct PDF URL pattern is https://www.etsi.org/deliver/etsi_ts/<range>/<number>/<version>/ts_<number>v<version>p.pdf, and browsing the parent directory — for example https://www.etsi.org/deliver/etsi_ts/102900_102999/102941/ — lists every published version, which is the fastest way to check whether a newer revision exists.
Nine documents, in the order that actually works.
| Order | Document | Why |
|---|---|---|
| 1 | ETSI EN 302 665 | The ITS station architecture. Everything else hangs off this. |
| 2 | ETSI TS 103 900 (CAM) and EN 302 637-3 (DENM) | The two messages you will implement first |
| 3 | ETSI TS 103 097 V2.2.1 (March 2026) | The security envelope and certificate profile. Note it now profiles IEEE 1609.2-2025. |
| 4 | ETSI TS 102 941 V2.2.1 (November 2022) | The PKI protocol — enrolment and authorisation message flows. This is the one you will read five times. |
| 5 | ETSI TS 102 940 V2.1.1 | The security architecture and the privacy requirements, including synchronised ID change |
| 6 | ETSI TS 103 301 V2.3.1 (April 2026) | Infrastructure services — SPATEM, MAPEM, IVIM, SREM, SSEM |
| 7 | ETSI TS 103 759 V2.2.1 (January 2026) | Misbehaviour reporting |
| 8 | ETSI TS 103 324 (CPM) and TS 103 300-3 (VAM) | Day-2 |
| 9 | RFC 8902 | TLS 1.3 authentication using ITS certificates — free, short, and the bridge to session-based security |
Free, and the fastest way to get real.
ETSI hosts them on its GitLab at forge.etsi.org.
- IEEE 1609.2 modules:
https://forge.etsi.org/rep/ITS/asn1/ieee1609.2 - TS 102 941 PKI modules:
https://forge.etsi.org/rep/ITS/asn1/pki_ts102941 - Common data dictionary and facilities:
https://forge.etsi.org/rep/ITS/ITS_ASN1 - Mirror organisation:
https://github.com/etsi-forge
Compile them with asn1c (C) or asn1tools / pycrate (Python). The wider open-source toolchain →
IEEE, SAE, ISO and CEN.
- IEEE — paid, via IEEE Xplore or resellers. The current texts are IEEE 1609.2-2025 (published 29 May 2026, superseding the 2022 edition) and IEEE 1609.2.1-2026 (published 3 July 2026). Whether the 1609 family is in the IEEE GET free programme is unconfirmed, so do not assume it is. A publicly posted consolidated 1609.2 draft exists on the ETSI Plugtests wiki — useful for orientation, but it is a draft, not the published text.
- SAE — paid. J2735 (message set dictionary), J2945/x (performance requirements), J3161/1 (the US C-V2X deployment profile). What each contains →
- ISO / CEN — paid. ISO 21177:2023 for ITS station security services.
Five that are more useful than most of the paid ones.
- EU C-ITS Certificate Policy Release 3.0 (May 2024) and the CPOC Protocol Release 1.1, both at
cpoc.jrc.ec.europa.eu - CAR 2 CAR Communication Consortium Basic System Profile — the RS_BSP requirement IDs European OEMs build to. The parameters that actually ship →
- BSI TR-03164 — German C-ITS guidance, free from bsi.bund.de
- Brecht et al., “A Security Credential Management System for V2X Communications” — the single best free document on SCMS internals, with the full butterfly key and linkage value mathematics
- 5GAA publications — particularly “Credential Management Supporting V2X Commercial Deployments” (July 2025) and the Misbehaviour Detection white paper (2022)
Where this fits.
Message sets
Every message these standards define, with IDs and rates.
V2X PKI
TS 102 941 clause by clause, with the nesting order.
Open source
The stacks and compilers that implement all of this.
Ref: IEEE 1609.2
Field-by-field certificate reference, with the COER encoding and an X.509 comparison.
Ref: ETSI TS 102 941
V2X PKI architecture reference — EA, AA, EC/PC issuance, butterfly expansion, CRL and CTL distribution.
Ref: ETSI TS 103 097
SecuredMessage wire-format reference — header info, SignerInfo modes, CAM/DENM/SPaT/MAP profiles.
Ref: ISO 21177
ITS station session-layer security — secure-session establishment and certificate-based mutual authentication.
PKI test environments
Where to exercise TS 102 941 against a real authority.
Test and certification
What conformance to these standards is actually assessed against.
Questions this page answers.
Are V2X standards free?
The European ones are. ETSI publishes every deliverable at no charge, including the security specifications TS 103 097, TS 102 941 and TS 102 940, and the ASN.1 modules are free on ETSI's GitLab. IEEE and SAE standards are paid, as are ISO and CEN. EU C-ITS policy documents, including the Certificate Policy, are free.
Where do I download the IEEE 1609.2 ASN.1 modules?
ETSI mirrors them on its GitLab at forge.etsi.org/rep/ITS/asn1/ieee1609.2, free, alongside the TS 102 941 PKI modules and the common data dictionary. Compile with asn1c for C or asn1tools or pycrate for Python.
What is the current version of IEEE 1609.2?
IEEE 1609.2-2025, published 29 May 2026, superseding the 2022 edition. IEEE 1609.2.1-2026 superseded 1609.2.1-2022 in July 2026. ETSI TS 103 097 V2.2.1, published March 2026, profiles the 2025 base standard. Anyone writing 1609.2 code in 2026 should be working from the 2025 text.
What is the difference between IEEE 1609 and ETSI ITS?
Two complete, parallel stacks for the same job. IEEE 1609 — the WAVE family — is North American, uses SAE J2735 messages and IEEE 1609.2 security. ETSI ITS is European, uses CAM and DENM with GeoNetworking, and ETSI TS 103 097 security profiling IEEE 1609.2. They share cryptography and certificate format lineage but are not interoperable above that.